Prosecutors have instead charged the intruder's alleged accomplice, 29-year-old Dustin Stewart, with first-degree murder in the death of his friend, Justin Shane Martin, 24.

Police said the two men broke into 18-year-old Sarah McKinley's mobile home in Blanchard, Okla., the evening of Dec. 31, while the young widow was home with her baby. McKinley's husband had died the week before, on Christmas Day, of lung cancer.

McKinley told police that Martin had stopped by the house on the day of her husband's funeral claiming he was a neighbor who wanted to say hello.

On New Year's Eve, Stewart joined Martin, who this time was armed with a 12-inch hunting knife. Police said the two men may have been high on prescription painkillers and looking for more drugs in McKinley's home.

As one of the men went from door to door outside her home trying to gain entry, McKinley told ABC News' Oklahoma City affiliate KOCO that she quickly got her 12 gauge, went into her bedroom and got a pistol, put a bottle in the baby's mouth and called 911.

"I've got two guns in my hand. Is it OK to shoot him if he comes in this door?" the young mother asked the 911 dispatcher. "I'm here by myself with my infant baby. Can I please get a dispatcher out here immediately?"

The 911 dispatcher confirmed with McKinley that the doors to her home were locked as McKinley asked again if it was OK to shoot the intruder if he came through her door.

"I can't tell you that you can do tha,t but you do what you have to do to protect your baby," the dispatcher told her. McKinley was on the phone with 911 for 21 minutes.

When Martin kicked in the door, the young mother shot and killed him. According to court documents, Martin was holding a knife when he died.

Authorities called McKinley's actions justified because she clearly acted in self-defense. Oklahoma law permits the use of deadly force against intruders.

Stewart, who ran away from McKinley's home after hearing the gunshots but later turned himself in to police, was charged in Martin's death.

"When the death of someone occurs in commission of a felony, we're allowed to file a murder charge, and that's what we've done in this particular case, because Mr. Stewart, in this case, will be responsible for the death of Justin Martin," said District Attorney Jason Hicks.

Stewart was arraigned Wednesday and was being held in the Grady County jail as he awaits a bond hearing.

While Stewart sits in jail, McKinley has been hailed as a hero and received an outpouring of support from neighbors who have nicknamed her the "Make My Day Mom."

The Blanchard community has poured in monetary and clothing donations for McKinley, who explained her actions by saying, "There's nothing more dangerous than a woman with a child.

"I wouldn't have done it, but it was my son," she told KOCO. "It's not an easy decision to make, but it was either going to be him or my son. And it wasn't going to be my son."